The present invention is generally related to the field of fiber optic connectors and, more particularly, to an advanced fiber optic contact that includes active components.
An electronic rack assembly can define one or more positions each of which is configured for receiving a module. The rack assembly can include a connection back plane such that each module can include a complementary connection arrangement that blind-mates to the connection back plane when each module is installed. In this way, a large number of interface connections can simultaneously be made or broken such that each module can be conveniently installed and/or replaced. Such rack assemblies, by way of example, have become popular in the avionics field.
Data rates have increased between modules, at least in the avionics field, due to a desire to provide for high-definition digital video for in-flight entertainment systems, cockpit displays, AFDX (Avionics Full Duplex Switched Ethernet) interconnect protocol and the like. Accordingly, avionics systems and aircraft manufacturers hope to take advantage of the extremely high bandwidth and light weight, ease of routing, and immunity to electromagnetic interference (EMI) offered by the optical fiber transport medium. There is a need, therefore, for avionics rack assemblies and associated modules to accommodate fiber optic connections therebetween. Some standards such as the ARINC 801-804 standards, by way of non-limiting example, detail specifications for fiber-optic connector interfaces that can be inserted into an ARINC module connector, as well as into rack connectors. These standards pertain to passive optical connectors for blind-mate interfaces that are inserted into industry-standard “Size 8” cavities, so-named due to the approximate 8 mm diameter of the cavity.
One approach that has been taken on the module side in such systems employs an optical converter component inside of the module. The optical converter is mounted on a printed circuit board and can support an optical fiber that serves as a pigtail leading to an ARNIC 801 passive fiber-optic connector for connection to the module external interface. During assembly of a module such as an avionics module, fibers associated with such optical converter modules must be routed very carefully through the module between the optical converters and the module interface. This is fundamentally an operation not suited to automated assembly techniques, and requires a relatively skilled technician. In this regard, optical fibers are easily susceptible to damage due to excessively small bend radius, high heat, handling errors, and the like. Therefore, as packaging densities of avionics modules have increased, the routing of optical fibers inside of a module has become problematic. Since manufacturing of modules incorporating both optical fibers and electrical cabling between circuit boards requires operators with specialized training and skill to handle, terminate, dress, and restrain the optical fibers so that they survive the rigors of the aerospace environment, assembly costs for avionics manufacturers are driven upward and the number of available contract manufacturers is limited to those with fiber-optics manufacturing expertise. While the example of “avionics modules” is used here as a primary example, it is noted that the problems described herein with realizing fiber-optic interfaces in electronics modules pertain to application in many other fields, and the usefulness of the invention described herein is therefore not limited to the avionics industry.
Another prior art approach attempts to provide for the use of optical fiber, for example, in an overall avionics environment external to modules while eliminating the need to route optical fiber within the avionics module itself. Generally, this approach moves the optical converter into the module interface. One example of a prior art attempt that adopts this approach is seen in U.S. Pat. No. 7,690,849 (hereinafter, the '849 Patent). The patent teaches an “active optical contact” for use in size-8 cavities in ARINC connectors and incorporates its conversion hardware entirely into the size-8 contact body.
In the '849 Patent, the optical converter is soldered to a longitudinally-mounted printed circuit board (PCB). The same PCB supports electrical interface pins on an opposing end thereof having internal ends which are also soldered to the PCB. The entire PCB is then sealed into a contact body using an epoxy potting material such that projecting or external ends of the interface pins project outwardly for purposes of externally electrically interfacing the contact. Applicants recognize that this design is problematic for a number of reasons. For example, the optical connection of the optical converter is positionally fixed and cannot float or move with resilient axial biasing to effectively accommodate blind-mating, for example, in accordance with ARINC requirements that are set forth for passive fiber-optic connectors. At the same time, the configuration of the electrical interface pins, for external electrical connection, is constrained based on connecting to one or both surfaces of the PCB. The limitations on pin location can become serious when it is remembered that the diameter of the contact body can be very small in the first instance. Another concern arises, based on this design, when it is desired to form solder connections to the projecting ends of the electrical interface ends since the soldering process used to attach the unit to an external PCB is constrained to the use a solder having a significantly lower melting temperature than the solder used to attach the internal ends of the pins to the PCB. This is especially problematic when non-leaded solders are mandated to satisfy the requirements of RoHS (Reduction of Hazardous Substances) act of the European Union. These concerns as well as related concerns may be addressed at one or more appropriate points hereinafter.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.